On late Sunday, a powerful 997-millibar storm and associated warm and cold fronts are developing about 100 miles west of San Francisco, but it will move southeastward toward the Central Coast. On Monday morning, the warm front will pass the Central Coast and it might generate the massive amount of rain showers and moderate to fresh southerly winds at a predicted speed from13 to 24 mph. A well-marked cold front will follow on Monday afternoon into Monday night with increasing the rainfall and southeasterly winds. Moderate gale-force to fresh gale-force at a predicted speed at 32 to 46 mph southeasterly winds with gusts of at least 55 mph might be established along the coastline around midnight with the frontal passage.
On Tuesday morning, the 997-millibar storm will travel southeastward and it will pass through San Luis Obispo and Santa Barbara counties with moderate gale-force to fresh gale-force at a predicted speed at 32 to 46 mph southwesterly winds with gusts of at least 55 mph along the shoreline. Rainfall rates might become heavy on Monday night through Tuesday morning. Rain showers will be produced behind the cold and unstable air. On Tuesday afternoon and night, there will be randomly heavier rain and there might be a chance for thundershowers. The system might tap into subtropical moisture and it will generate widespread moderate to heavy rain. The temperatures are expected to be significantly mild and it will bring heavy snow to the Sierra Nevada due to the subtropical nature of this system.